1. Technical Field
The present invention relates to wireless communication, and more particularly, to a wireless transceiver in a wireless communication network and a relay station including the wireless transceiver.
2. Related Art
Wireless communication systems are broadly used to provide various types of communication services. A wireless communication system may be a multiple access system that can support communication with multiple users by sharing usable system resources such as bandwidths and transmission power. The multiple access system may include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) systems and a single carrier frequency division multiple access (SC-FDMA) system.
The wireless communication system typically includes a base station (BS) providing services to a cell that is a predetermined area around the BS. Normally, a terminal or a mobile station (MS) may communicate with the BS in service coverage of the BS. However, data communication with the BS can be disabled or communication quality may be degraded due to an obstruction such as a building or in an edge area of the cell.
Various methods have been suggested in order to expand the service coverage of the BS. One of the methods is to use a relay station (RS) in the wireless communication system. Here, the RS relays data communication between a BS and an MS (two MSs, or an MS/BS and another RS). In other words, the RS enables data communication between the BS and a distant MS by using two-hop or multi-hop links rather than a single direct link. As such, the RS can expand cell coverage and improve cell edge performance of the BS. Also, the RS can use this approach to improve a cell throughput.
Some RSs use a time division duplex (TDD) wireless communication system such as a mobile WiMAX system (e.g., IEEE 802.16j/m). The TDD wireless communication system can play the role of the RS without modifying an internal configuration or an operation method of a wireless transceiver of a legacy TDD station. In more detail, a TDD RS relays data communication between the BS and the MS by accessing an uplink or downlink channel at a scheduled time according to uplink/downlink slot allocation and resource scheduling information.
Recently, a RS relay concept has been considered as a way to improve the performance of a next generation frequency division duplex (FDD) wireless communication system. The next generation FDD wireless communication system includes, for example, an FDD-based third generation project partnership (3GPP) long-term evolution (LTE) system or a mobile WiMAX system supporting FDD.
However, the internal configuration or the operation method of the wireless transceiver of the legacy FDD station is incompatible with that of a wireless transceiver of an FDD RS. In more detail, it is assumed that a downlink frequency between an FDD BS and an FDD MS is a frequency f1 and an uplink frequency is a frequency f2 in the FDD wireless communication system. A legacy BS transmits data on the frequency f1 and receives data on the frequency f2, and a legacy MS receives data on the frequency f1 and transmits data on the frequency f2. Accordingly, the FDD RS should be able to receive data on the frequency f1 (downlink) and transmit data on the frequency f2 (uplink) at one time, while it should be able to transmit data on the frequency f1 (downlink) and receive data on the frequency f2 (uplink) at another time. However, the FDD RS requires additional features for transmission/reception (Tx/Rx) band switching. These features are not included in the conventional wireless transceiver used in the legacy FDD station.
As described above, transmission/reception (Tx/Rx) band switching is not performed by the FDD BS and the FDD MS and thus a wireless transceiver of the FDD BS or the FDD MS may not be used as the wireless transceiver of the FDD RS. In order to be used as the wireless transceiver of the FDD RS, at least Tx/Rx band switching (swapping) capability is required. Also, the FDD BS can communicate with the FDD MS in various scenarios and the FDD RS should be able to support data communication according to the various scenarios.